The present invention relates to a polyethylene-2,6-naphthalate film comprising a resin composed mainly of polyethylene-2,6-naphthalate and having an intrinsic viscosity .eta. in the range of from 0.31 to 0.6, said film having stretch ratios of 1 to 3 times and 1 to 3 times or 3 to 6 times and 1 to 1.8 times respectively in substantially mutually perpendicular directions and a thickness in the range of from 5 to 150 .mu.m;a polyethylene-2,6-naphthalate resin comprising a blend composed mainly of two components of: a polyethylene-2,6-naphthalate resin having an intrinsic viscosity in the range of from 0.3 to 0.5 dl/g and prepared by an esterification reaction of a dicarboxylic acid having a 2,6-naphthalenedicarboxylic acid content of not less than 90% by mole with a glycol having an ethylene glycol content of not less than 90% by mole, or a transesterification and a polyethylene-2,6-naphthalate resin having an intrinsic viscosity in the range of from 0.5 to 0.7 dl/g and prepared by an esterification reaction of a dicarboxylic acid having a 2,6-naphthalenedicarboxylic acid content of not less than 90% by mole with a glycol having an ethylene glycol content of not less than 90% by mole, or a transesterification, the resin blend having an intrinsic viscosity in the range of from 0.31 to 0.68 dl/g;a modified polyethylene-2,6-naphthalate resin prepared by an esterification reaction of a dicarboxylic acid having a 2,6-naphthalenedicarboxylic acid content of not less than 90% by mole with a hydroxy compound having an ethylene glycol content in the range of from 90 to 99.5% by mole and a content of a compound having three or more ester forming functional groups in the range of from 0.5 to 5% by mole, or a transesterification; andpackaging films or packs produced from these resins.